Influence of stress state on the evolution of misfit dislocation networks in a Ni‐based single crystal superalloy

Abstract

The structural evolution of interfacial dislocation networks in a Ni‐based single crystal superalloy under various stress states was simulated by molecular dynamics (MD). From the simulation, we found that the dislocation network exhibits different deformation and damage mechanisms under various stress states. The square dislocation network at the (100) phase interface is the easiest to damage under a [100] uniaxial load, but more difficult to damage when multi‐axial loads are applied. This suggests that the application of a [100] direction axial load is the key factor for the damage of the square dislocation network, which leads to failure of the Ni‐based single crystal superalloy under the [100] axial centrifugal load. Moreover, based on MD simulations, the effects of the stress state on γ′ rafting were explored. The results indicate that the morphology of γ′ raft depends on the damage structures of the dislocation network under various stress states.

Keywords:

• Ni‐based single crystal superalloy
• molecular dynamics simulation
• raft morphology
• dislocation network

Acknowledgements

The research was supported by National Natural Science Foundation of China (Grant Nos. 11072026 and 11102139), the Fundamental Research Funds for the Central Universities (Grant No. 2009JBZ015) and China Postdoctoral Science Foundation (Grant No. 20110491205). The third author is also grateful to the National Basic Research Program of China (Grant No. 2010CB732104).